When Jayson Tatum stepped onto the court at Xfinity Mobile Arena Tuesday night, he momentarily lost track of time.

“I couldn’t tell if it was November 10 or June 10. It felt like a [expletive] Finals game.”

Considering all the hype surrounding the matchup, it was easy to understand why.

The top two teams in the Eastern Conference were squaring off in a highly anticipated early-season showdown. A revamped, deep Celtics squad was facing an All-Star-laden Philadelphia team. And, of course, there was the added intrigue of Boston facing former Celtic Jaylen Brown for the first time.

There was no shortage of noise leading up to the game. But once the ball was tipped, Tatum and the Celtics went about blocking it out.

Boston marched into a hostile road environment and turned one of the most anticipated matchups of the young NBA season into a one-sided affair, blowing the 76ers out of their own building, 123-101.

And while the game carried plenty of emotional weight, Tatum never allowed the moment to get the better of him.

“I thought he handled it beautifully,” Paul George said of his All-Star teammate. “I thought we put more on this (game) than we should have.”

Tatum has long prided himself on maintaining an even keel, regardless of the circumstances. Tuesday night was another example of that approach paying off.

“I’ve kind of been this way since I was a kid,” he said. “Never too high, never too low. Give a lot of credit to my mom. I’ve always had good perspective on things.”

That mentality hasn’t gone unnoticed by his head coach.

“His mental toughness is underrated. His emotional stability is underrated. His emotional intelligence is underrated,” Joe Mazzulla said. “His ability to just stay focused on what matters most is one of his best gifts.”

For Tatum, that meant doing whatever was necessary to help his team win, even if he wasn’t the one dominating the scoring column. He spent much of the night operating in an off-ball role, finishing with 21 points, six rebounds, four assists, and two blocks while setting the tone with his defensive effort and willingness to do the dirty work.

Though he did have quite the loud dunk on LeBron James, similar to the poster he put on The King in Game 7 of the Eastern Conference Finals his rookie season.

George, meanwhile, took center stage offensively. Despite making his return to Philadelphia, the nine-time All-Star was one of the more overlooked storylines entering the matchup. That changed in a hurry as he poured in a game-high 36 points, including six 3-pointers on 11 attempts.

Fourteen of those points came during the fourth quarter. Prior to that point, it was a relatively close game. The matchup was tied at 79-79 with 3:05 remaining in the third quarter, before the Celtics took control, unleashing a 39-10 run that broke the game open.

Boston carried a nine-point advantage into the fourth before opening the final frame on a 14-0 burst. Payton Pritchard got things rolling with back-to-back 3-pointers, and George followed with eight consecutive points to stretch the lead to 23.

Much of that damage came with Tatum watching from the bench, a stretch that George views as one of his most important responsibilities.

“Those are the minutes that I’m always trying to win to give him as much rest as possible, to where when he comes in, it’s no pressure that he has to kind of get the game back under control,” George explained. “He can come back and kind of float, get himself back going.”

It was exactly the type of two-way impact Mazzulla has come to expect from his veteran star.

“I thought he was great,” the coach said. “That’s just what we need. We need him to play two-way basketball and be great. And you saw that there, especially at the start of the fourth quarter.”

The performance was particularly impressive with it being George's return game to Philly. But when asked whether he felt the need to make a statement against his former team, he quickly redirected the attention toward his teammate.

“Nah. My job is to come in and support JT and be the best version that I can be for him. That was my only focus.”

That selfless approach has become a defining characteristic of this Celtics group. Rather than worrying about who gets the most shots or the biggest moments, Boston has embraced a collective mentality in which individual success is celebrated throughout the locker room.

“We want to see the next man win. We want to see PG kill. We want to see JT go off,” Pritchard said. “Like it really matters. So everybody’s gonna have their nights and we love to see it.”

It’s a connection that has been building since the summer, when a roster filled with new faces began coming together both on and off the court.

“You see how much fun we have off the court by how we play on the court,” George said.

That chemistry has translated into early success. The Celtics are now 8-1 with Tatum and George in the lineup, their lone defeat coming on opening night. And while the partnership is still in its infancy, Tatum sees plenty of room for growth.

“I don’t want to put a ceiling on it,” he said. “I think two guys, obviously, very capable of doing a lot of things on the court … It’s just how do we continue to build off this?”

Tuesday’s performance offered a promising glimpse of what’s possible when Boston’s two stars are clicking and the rest of the roster is operating in sync. And that wasn't just the case on offense. Boston's defense held Philadelphia to just one 20-point scorer in Tyrese Maxey, who finished with 24. Brown, meanwhile, was limited to 13 points, five rebounds, and two assists while posting a game-low minus-27 in 26 minutes.

It was the type of complete performance that could provide a significant confidence boost for a team developing its identity.

But as much as this matchup meant to the players, coaches, and everyone watching, Boston wasn’t about to let one November victory become anything more than that. As Tatum recalled hearing from Brad Stevens years ago, every game counts the same in the standings. That perspective has stuck with him, serving as a reminder to remain present rather than get caught up in the magnitude of any single matchup.

And with the Celtics headed straight to Toronto for the second night of a back-to-back, there was little time to dwell on their latest win.

“We’ve gotta get on a plane tonight and we’ve got another game tomorrow against a good Toronto team,” Tatum said.

Mazzulla echoed that message, turning the focus from what the Celtics had just accomplished to what awaited them less than 24 hours later.

“This was an opportunity and a test, playing against one of the best teams in the league. Highly talented team,” he said. “Now the question is: Who do you want to be? We play in less than 24 hours. Who do you want to be tomorrow?”